This invention relates to a lever mechanism which may be affixed to a plurality of valve stems by appropriate cable and push rod assemblies for control thereof. In particular, it relates to a single-control lever mounted in a bracket assembly which has generally linear travel to control at least two valve stems in a construction machine.
Control of hydraulic circuits in machinery, particularly construction machinery of the mobile type, for example, tracked vehicles, is generally accomplished through lever mechanisms. Operation of these various lever mechanisms is best accomplished with a minimum change of directions of the lever during positioning in the various operable positions. For example, in a tracked vehicle having a winch mechanism affixed to the rearward end of the vehicle it is appropriate to provide control of the winch by fore and aft movement of the winch control lever. Simple fore and aft control motion is more appropriate than combined lateral and fore and aft motion for winch control in that the operator may observe the particular load being winched into or away from the winching vehicle. To utilize the more conventional and somewhat complex winching patterns for control of a plurality of valve stems associated with such a winch mechanism tends to divert the operator's attention from the job at hand.
A problem associated with a single-control lever in such a winching system is the necessity of controlling a plurality of valve stems. In any winching system, it is appropriate to select the direction the winch is to be rotated and secondly, to control the fluid rate delivered to the winch in order to control the speed of the winch and concurrently release any brake associated with the winch. Thus, a control lever must first select the direction of rotation of the winch, release the winch brake, and then finally, modulate fluid flow to the winch motor in accord with the desired rate of speed. To accomplish this in a two-directional (i.e., reel-in and reel-out) lever mechanism requires a particularly unique design since modulation control must be operable in both the reel-in and reel-out criteria.
Although this problem has been described in relation to a winch operation, it should be apparent to those skilled in the art that a single-control lever to control a plurality of valve stems is not unique to the winch problem. Accordingly this invention is equally applicable to other hydraulic control systems.